Such prior application discloses a horizontal barometric leg of the type shown in Pagan U.S. Pat. No. 4,783,291. In the Pagan patent, a vacuum chamber includes an extrusion die at one end forming an extrudate. After passing through sizing, calibration and draw off equipment, for example, the extrudate exits the vacuum chamber through a water baffle. The extrudate passes over a dam and dips into a pond to exit the chamber through the pond. The pond has two sections or levels, one with a higher level within the chamber during vacuum and one with a lower level outside the chamber. A circulating system keeps the pond level within the chamber from overtopping the dam during vacuum extrusion. The pond provides full immersion cooling during vacuum extrusion as well as providing a continuous water baffle seal for the extrudate exiting the chamber. The extrudate may be cut and processed in atmosphere after it leaves the lower level or section of the pond outside the chamber.
In such prior Lightle, et al. application there is disclosed a horizontal barometric leg vacuum extrusion line with a support truss extending from the dam to a fixed bulkhead, the die being mounted on the end of the extruder projecting through the fixed bulkhead. Calibration and sizing or draw-off equipment is mounted on the truss.
The chamber surrounding the truss includes a fixed section and a telescoping section which can move away from the bulkhead telescoping over the fixed section to provide access to the die and the downstream equipment.
If some of the downstream equipment is within the fixed section, the fixed section is entered as one would a cave or tunnel. The system with the single movable section telescoping over the fixed section is quite adequate for medium to low through-puts, but is not necessarily adequate for large through-puts and/or extrudate cross-sections with foaming extrudates. Through-puts are normally expressed as pounds or kilograms per hour. For example, smaller through-puts typically may be two hundred pounds per hour or less, while larger through-puts may typically be two thousand pounds per hour or more.
When a mishap or mayhap occurs, especially during system start-up, the operators need to open the chamber quickly and obtain access to the errant downstream equipment quickly. The operators not only need access quickly, they need access with an adequate spatial working environment. Without such, the vacuum chamber may literally fill up or start to fill up with extrudate, especially foam extrudate, requiring the whole system to be shut down.
With higher through-puts, problems need to be addressed more quickly, and the chamber of the system requires larger volume around the downstream equipment, not only to accommodate the equipment, but also operators around the equipment with adequate spatial working environment to obtain access to the equipment and any misdirected extrudate.